1. Division of General Dentistry, Tokyo Dental College Chiba Hospital, 1-2-2 Masago, Chiba 261-8502, Japan
2. Division of General Dentistry, Department of Clinical Oral Health Science, Tokyo Dental College, 2-9-18 Misaki-cho, Chiyoda-ku, Tokyo 101-0061, Japan
3. Division of Biomaterials Research, Oral Health Science Center, Tokyo Dental College, 2-9-18 Misaki-cho, Chiyoda-ku, Tokyo 101-0061, Japan